B3055 on 2020-2025 Buick Encore GX: No Start, Security Light Causes and Fixes

What's Unique About the 2020-2025 Buick ENCORE GX

The 2020-2025 Encore GX is built on the GM VSS-F platform, which features a modern electrical architecture shared with the Chevrolet Trailblazer. This platform relies on a push-button start system where communication between the key fob and the car is constant. This system is particularly sensitive to radio frequency (RF) interference from aftermarket devices like phone chargers and dash cams, a condition noted in GM technical service bulletins. Unlike older GM vehicles with a physical key, a dead key fob battery is a more common cause for this code, but Buick provides a backup pocket in the center console to allow the car to start even with a dead fob, a crucial feature for owners to know.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Engine will not crank or start.
• Engine starts and then immediately stalls.
• Security light is illuminated or flashing on the dashboard.
• "No Fob Detected" or "NO REMOTE DETECTED PLACE KEY IN KEY POCKET THEN START YOUR VEHICLE" message on the driver information center.
• Remote start does not work.
• Vehicle electronics (radio, lights) turn on, but the engine does not engage.
• Have to place the key fob in the center console pocket to start the vehicle.

Most Likely Causes

1. Radio Frequency Interference (RFI) 🔴 High Probability As noted in TSB PIC5650M, the VSS-F platform's electronics are sensitive to RFI from aftermarket devices like phone chargers, dash cams, or even other RFID cards on the keychain. This interference can block the low-frequency signal from the key fob.
   How to confirm: Unplug all aftermarket devices from 12V and USB ports. Remove all other keys and access cards from the keychain. If the car starts, RFI was the issue. Reintroduce devices one by one to isolate the source.
   Typical fix: Remove the source of interference. Use high-quality, shielded electronic accessories.
   Est. part cost: $0
2. Weak or Dead Key Fob Battery 🔴 High Probability Keyless entry systems constantly communicate with the vehicle, leading to faster battery drain. The required battery is a CR2032.
   How to confirm: Try starting the vehicle with your spare key fob. Alternatively, place the problematic key fob in the designated transmitter pocket in the center console storage area (with buttons facing forward); if the car starts, the battery is the culprit.
   Typical fix: Replace the CR2032 battery in the key fob. This can be done at home with a small tool to pry the fob case open. 🎬 Watch: Step-by-step guide to replacing your key fob battery.
   Est. part cost: $5-$15
3. Faulty Key Fob 🟡 Medium Probability The internal transponder chip or its circuitry can fail from being dropped, water damage, or age. A Reddit user described a scenario where even a new, professionally programmed key failed to work, pointing to a deeper issue but starting with a faulty key is common.
   How to confirm: If the vehicle starts with the spare key but not the primary key (even after a battery change and checking for RFI), the primary key is faulty.
   Typical fix: The key fob must be replaced and professionally programmed to the vehicle by a dealer or qualified automotive locksmith. The OEM part has FCC ID HYQ4ES. 🎬 Watch: Professional locksmith programming a new 2024 Encore GX key.
   Est. part cost: $150-$400
4. Body Control Module (BCM) Issue ⚪ Low Probability TSB #PIC5650M points to intermittent no-start conditions involving B3055 and other codes, suggesting a potential underlying software or hardware fault in the BCM that GM is aware of. This is the module that processes the key's signal.
   How to confirm: This is a diagnosis of exclusion. If keys are good, batteries are fresh, and there is no interference, a technician must use a GM-specific scan tool to check BCM communication, software status, and look for internal faults.
   Typical fix: May require a BCM software update, reprogramming, or complete replacement by a dealership. This requires access to GM's Service Programming System (SPS).
   Est. part cost: $500-$1200

Rare But Worth Checking

• Faulty Keyless Entry Antenna/Receiver: The vehicle has multiple antennas to receive the signal from the key fob. If one of these fails, it can cause a localized "No Fob Detected" issue. A locksmith on Reddit mentioned this as a possible cause when a new key fob is recognized by their tool but not by the car. Diagnosis involves using a scan tool to monitor the signal strength received by the BCM from each antenna.
• Wiring Harness Damage: A break or short in the wiring between the keyless entry antenna and the BCM can cause a loss of signal. This is rare but can be caused by previous repairs, rodent damage, or corrosion.

Diagnosis Steps

1. Check for a security light on the dashboard when trying to start the vehicle. This confirms an anti-theft issue.
2. Remove all aftermarket phone chargers, dash cams, and USB adapters from the vehicle to eliminate potential Radio Frequency Interference.
3. Replace the battery in the key fob with a new CR2032.
4. Try starting the vehicle with your spare key. If it works, the original key is the problem.
5. If the key fob battery is dead or suspected to be weak, place the fob in the transmitter pocket located in the front cupholder/storage area of the center console and attempt to start the engine. The 2022 owner's manual specifies placing it with the buttons facing the front of the vehicle.
6. Use an OBD-II scanner capable of reading BCM codes to confirm B3055 is active and check for other related codes like B3060 or B3935.
7. If the problem persists, the vehicle requires professional diagnosis to inspect the BCM, wiring, and keyless entry antennas using specialized equipment like a GM GDS2 or Techline Connect.

Parts You'll Likely Need

• Key Fob Battery (OEM #CR2032) — This is the most common and simplest fix for a key that is not being detected.
  Trusted brands: Energizer, Duracell, ACDelco
  OEM price range: $5-$15
  Aftermarket price range: $5-$10
• Keyless Entry Remote (Key Fob) (OEM #13547675 (GM), 13530511 (GM), FCC ID: HYQ4ES) — If the internal transponder fails, the entire key fob must be replaced and programmed. Ensure the FCC ID and button configuration match the original remote.
  Trusted brands: ACDelco, GM Genuine Parts
  OEM price range: $150-$300
  Aftermarket price range: $70-$150

Related Codes That Often Appear With This One

• B3060 — This code means 'Unprogrammed Transponder' and can appear with B3055 during a key programming failure or a general security system fault.
• B3935 — This code for 'Transponder Authentication Failed' means a signal was received but was incorrect. It often accompanies B3055 when the system is malfunctioning.

Technical Service Bulletins (TSBs) & Recalls

• PIC5650M: Addresses an intermittent no crank, no start, or start stall concern with the security light coming on, where DTCs including B3055 may be found. It points towards RFI as a potential cause.
• PIT5030E: While for slightly older models, this TSB is relevant as it shows a history of B3055 being set due to minor key-related issues, such as a flip-key not being fully extended, which interrupts the signal to the transponder.

Platform-Specific Known Issues

• A known issue documented in TSB #PIC5650M describes an intermittent no crank, no start, or stall condition with the security light on, where DTC B3055 may be set. This bulletin suggests a potential underlying module or communication issue that the manufacturer is aware of.
• An older, related TSB for other GM vehicles (PIT5030E) highlights how even the physical orientation of a flip-key (if not fully extended) could cause a B3055 code, illustrating the system's sensitivity.

Mechanic-Grade Diagnostic Values

• Resistance of BCM ground circuit to chassis ground — expected: Less than 10 ohms. Failure: A value greater than 10 ohms indicates an open or high resistance in the ground circuit, which can cause intermittent module operation.

Hidden / Shadow Codes Worth Checking

• B3055 00: This is the most common symptom byte seen with B3055. The '00' indicates 'No Sub Type Information,' meaning the base code contains all available fault information. (see via A dealer-level scan tool like the GM GDS2 or some high-end professional aftermarket scanners will display the code with its symptom byte.)

Scan Tool Commands That Help

• GM GDS2: Immobilizer Data / Remote Control Door Lock Receiver Data Display — Use this to view live data from the theft deterrent system. A technician can monitor parameters like 'Transponder Key Status' to see if it changes from 'Not Present' to 'Present' when a key is placed in the transmitter pocket, confirming if the antenna is reading the key.
• GM GDS2 / Techline Connect: Add or Replace Key Fobs — This function, found under the 'Remote Control Door Lock Receiver' module, is required to program new or additional key fobs to the vehicle's BCM.
• GM GDS2 / Techline Connect: Immobilizer Learn — This master function is necessary after replacing a major security component like the Body Control Module (BCM). It involves a security wait time and programs the new module to the vehicle and existing keys.

Wiring & Ground Locations

• Body Control Module (BCM) — Located in the center console, accessible by removing the lower panel on the front passenger side footwell.. The BCM is the central computer that receives and validates the key fob's transponder signal. All diagnostic wiring tests for the immobilizer system will originate or terminate at its connectors.
• Keyless Entry Transmitter Pocket — Inside the center console storage area, often in one of the cupholders or a dedicated slot.. This pocket contains a low-frequency antenna that can read the key fob even if the fob's battery is dead. If the car starts with the fob in the pocket but not otherwise, it confirms the issue is with the fob's battery or the car's main receiving antennas, not the fob's transponder chip itself.
• Ground G103 (Typical) — On many GM vehicles, this ground is located on the cowl in the engine compartment, often above the brake booster.. This ground point commonly serves the BCM and the Remote Door Lock Receiver. A loose or corroded G103 can cause intermittent power loss to the security system, leading to a B3055 code and other difficult-to-diagnose electrical issues.

OEM Part Supersession History

• 13530511 → 13532751, then 13547815 — Standard part evolution for design improvements or supplier changes.
  Heads up: An eBay listing suggests this supersession path; always confirm the latest part number with a GM dealer using the vehicle's VIN before ordering.

Model Year Variations Within This Range

• 2024-2025: The 2024 model year introduced a major interior refresh with a 'Virtual Cockpit,' featuring a combined 19-inch screen for the gauge cluster (8-inch) and infotainment (11-inch). This replaces the previous, more traditional setup. While the BCM's core function remains, this new digital interface changes how information is displayed and could have underlying software differences relevant to diagnosing network or module communication codes that may accompany B3055.